Tin-Based Bonding Material for Flexible Carbon Joints

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Solution Overview

Problem

Existing bonding materials face challenges in bonding carbon materials of varying shapes due to particulate form requirements and result in poor flexibility and high stress, leading to potential cracking, especially when using high Young modulus insert materials like silver, copper, and titanium.

Innovation Solution

A bonding material comprising 0.1 wt% to 5 wt% of compound-formable elements such as titanium, zirconium, or vanadium, primarily tin, which forms a compound layer with carbon, enabling flexible bonding with high tensile strength and maintaining heat conductivity by controlling the compound layer's thickness and composition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If high Young modulus insert materials (silver, copper, titanium) are used for bonding, then bonding strength is improved, but flexibility deteriorates and stress increases leading to cracking

Engineering Contradiction:
Improvebonding strengthVSAvoidflexibility
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The invention changes the material parameters by using low melting point metal (melting point 100°C to 500°C) instead of high Young modulus materials. This parameter change enables the bonding material to soften at low temperatures, providing flexibility while maintaining bonding strength through controlled compound layer formation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite structure with a compound layer formed between the bonding material and carbon material. This composite approach combines the low melting point metal with carbon-containing compounds, achieving both flexibility from the soft metal matrix and bonding strength from the interfacial compound layer.

Inventive Principle:
Principle #40Composite materials

2Strength

If conventional bonding materials are used, then bonding is achieved, but flexibility of the bonded structure deteriorates

Engineering Contradiction:
Improvebonding capabilityVSAvoidflexibility of bonded structure
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The invention fundamentally changes the thermal and mechanical parameters of the bonding material by selecting metals with melting points between 100°C and 500°C. This allows the material to remain soft and flexible at room temperature while still providing strong bonding through low-temperature processing and compound layer formation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The bonding material acts as a flexible interlayer between carbon materials, similar to how flexible films provide both bonding and flexibility. The low melting point metal creates a compliant bonding interface that accommodates deformation while maintaining structural integrity.

Inventive Principle:
Principle #30Flexible shells and thin films

3Strength

If carbon particles are used in bonding material, then bonding to carbon material is achieved, but flexibility deteriorates due to particulate form requirements

Engineering Contradiction:
Improvebonding to carbon materialVSAvoidflexibility
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The invention changes the physical state parameter of carbon in the bonding material from particulate (solid) to gaseous (carbon-containing gas). This allows the carbon to be uniformly distributed in the metal matrix without creating rigid particulate structures, maintaining both bonding capability and flexibility.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses carbon-containing gases (such as methane, acetylene, or carbon monoxide) instead of solid carbon particles. This pneumatic approach allows carbon to be introduced in a flexible gaseous state that can be uniformly distributed throughout the bonding material without compromising flexibility.

Inventive Principle:
Principle #29Pneumatics and hydraulics

4Strength

If high temperature baking (1700°C to 2100°C) is used for bonding, then bonding strength is improved, but manufacturing complexity and energy consumption increase

Engineering Contradiction:
Improvebonding strengthVSAvoidenergy consumption
Core Design Contradiction:
StrengthVSUse of energy by stationary object

Solution Approach 1:

The invention dramatically changes the temperature parameter from extreme high temperature (1700°C to 2100°C) to low temperature (100°C to 500°C melting point range). This parameter change reduces energy consumption while still achieving strong bonding through the formation of compound layers at the lower temperature.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention utilizes the phase transition (melting) of low melting point metals as the bonding mechanism. By heating to the melting point of the bonding metal (100°C to 500°C) rather than extreme temperatures, the material softens and forms strong bonds, then solidifies upon cooling to create a rigid but flexible joint.

Inventive Principle:
Principle #36Phase transitions

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution provides a flexible and strong bond between carbon materials, reducing the risk of cracking and maintaining heat conductivity, suitable for various applications including heat spreaders and semiconductor components.

Implementation Method 1

a compound layer which includes a compound of the compound-formable element, tin, and carbon is formed at an interface between the bonding material and the carbon material

Methodology Applied
Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

maintaining heat conductivity by controlling the compound layer's thickness and composition

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentEP3335828B1Manufacturing method of bonded body and bonded body obtained by the same
Publication Date: 2025.01.01 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP3335828B1 patent drawingFigure 1A~1B
  • EP3335828B1 patent drawingFigure 2A~2B
  • EP3335828B1 patent drawingFigure 3

AI summary

A bonding material includes at least 0.1 wt% to at most 5 wt% of at least one element which may form a compound along with tin and carbon, and Sn as the main component of a remainder.